Heat exchangers of the plate type are comprised of pairs of preformed plates joined to other pairs at their ends by integral bosses and separated at their middle section by air centers or corrugated fins, the plates and fins all being brazed together so that each pair of plates becomes a tube for carrying refrigerant, the bosses serving as a manifold for permitting refrigerant flow from one tube to another, and the fins facilitation heat exchange between the tubes and air flowing outside the tubes. U.S. Pat. No. 4,470,455 issued to Sacca describes such a plate type heat exchanger in detail. Special types or species of plates are used for the end plates of an assembly to provide fittings for external connections. Some special intermediate plate types are also used to define flow passages in the heat exchanger.
U.S. Pat. Nos. 4,860,421 and 4,900,328 issued to Breda et al and incorporated herein by reference disclose a machine for assembling plate pairs and subsequent placement into an array of plate pairs prior to brazing. The machine has a pair of rotors with indexing drive means for synchronously rotating the rotors, and pockets for receiving plates. The rotors, when indexed, each move a plate into a common mating plane such that the plates are joined together and the resulting plate pair falls into a fixture below for assembling the plate pairs into a heat exchanger core. The core is subsequently brazed to complete the joining of each plate pair as well as joining each pair to its neighbor at their bosses. Plates are supplied to the rotors by a stack of plates or a vertical magazine containing plates above each rotor and an escapement for releasing the plates from each stack one at a time to deposit the plates directly into the rotor pockets. Alternatively, one or both of the magazines is replaced by a plurality of magazines laterally spaced from the rotors and a shuttle or carriage selectively transfers plates from the magazines to the rotors. This arrangement permits different types of plates to be loaded in the several magazines so that special plate combinations can be constructed. Typically, that apparatus is operated with a magazine of regular plates directly feeding one rotor and a shuttle serving three magazines feeding the other rotor. The shuttle tends to slow down the operation because of the time it takes to move back and forth. If more magazines are served by a shuttle the distance travelled and the time consumed by the shuttle increases; the practical limit is three magazines per shuttle for an acceptable rate of production, which is greater then one plate pair per second. To have the capability of assembling a larger variety of plates it is desirable to have an improved method and apparatus for feeding plates to an assembly machine. Then the machine will have more flexibility in the type of cores it can make and the production rate is not decreased.